This invention relates to an automatic canceling device for a winker and more specifically it relates to an automatic electric canceling device for an automobile winker that unlocks the winker by means of suction power of a solenoid provided in the device even if the operating knob is located far from the steering shaft of the automobile.
A conventional automatic electric canceling device for an automobile winker typically comprises an operating lever which is pivotably fitted to a case and pivoted by an operating knob. A driving rod is slidably held by the lever by way of a compression spring and pressed against a juxtaposed cam unit. As shown in FIGS. 5(a) and 5(b), the cam unit comprises a fixed cam section 1 and a vertically movable cam section 3 provided in slit 2 which is located at the center of fixed cam 1. The fixed and movable cam sections 1 and 3 are respectively provided with grooves 4 and 5 to hold the winker operating lever in a neutral position. Fixed cam section 1 is provided with locking grooves 6 and 7 for firmly holding the winker operating lever respectively in left and right positions. The movable cam section 3 is biased downward by a spring and can be moved upward to unlock the lever by means of a solenoid which is energized by a release signal produced, for example, by a returning action of the steering wheel of the automobile.
A conventional automatic canceling device for a winker as described above operates in the following manner.
FIG. 5(a) illustrates a cam unit holding a winker operating lever in the left or right locking position. Under this condition, movable cam section 3 is found in a retracted position so that the surface of its groove 5 is aligned with the surface of locking groove 6 and that of locking groove 7 of fixed cam section 1 and the driving rod of the winker operating lever which is not shown in the drawing is engaged in locking groove 6 or 7 so that the winker operating lever is locked in the left or right locking position. Under this condition, the left or right winker is turned on and off to emit repeated flashes.
When the steering wheel is returned to the normal position, the switching mechanism of the winker is activated by a cam provided on the steering shaft to energize the solenoid. The energized solenoid moves movable cam section 3 upward against the pressure of the compression spring so that the surface of groove 5 of movable cam section 3 comes in alignment with the surface of groove 4 of fixed cam section 1 as shown in FIG. 5(b). Then the driving rod engaged in locking groove 6 or 7 is pressed by the surface of groove 5 of movable cam section 3 and moved toward central edge 6a of 7a of locking groove 6 or 7. At the position as shown in FIG. 5(b), the driving rod passes over central edge 6a or 7a and goes into grooves 4 and 5 which come to hold the rod in a neutral condition. Thereafter, the solenoid is deenergized and movable cam section 3 is moved downward by the compression spring to return to the position as shown in FIG. 5(a). At this stage, while movable cam 3 is moved downward and its groove 5 is disengaged from the driving rod, the winker operating lever is held in its neutral position as the rod comes into engagement with groove 4 of fixed cam section 1.
With an automatic canceling device of prior art as described above, the compression spring which is used to press the driving rod against cam groove 4 is required to have a considerable spring force in order to firmly hold the winker operating lever in the neutral position. This means that the spring force will become even greater when the driving rod comes into engagement with left or right locking groove 6 or 7. Since movable cam section 3 has to be pushed upward against the pressure of the compression spring to push the driving rod upward by the electromagnetic force of the energized solenoid, the spring force of the compression spring will be enormous when the lever is unlocked. Such a strong spring force in turn inevitably requires the use of a powerful and large solenoid in order to push movable cam section 3 upward against the pressure of the spring, consequently making it difficult to reduce the size as well as the cost of the solenoid.
In view of the above described and other problems of the prior art, it is therefore an object of the present invention to provide an automatic canceling system for a winker which requires only a relatively small force for activating cancelation of the winker so that the size as well as the manufacturing cost of the solenoid may be reduced.